With the digitalization of broadcasting, effective use of so-called TV white space, which allows secondary use of radio resources unused by primary users (broadcast, microphone, and the like) in a frequency band allocated for broadcasting use, is attracting attention. On the other hand, with the explosive growth of netbooks, portable AV players, tablet PCs, and the like, users using Wi-Fi (wireless LAN) are increasing. Further, the emergence of portable Wi-Fi routers or Wi-Fi smart phones results in an exponential increase in the number of Wi-Fi access points. Thus, the depletion of frequencies available for Wi-Fi use is expected.
Therefore, use of Wi-Fi technology in a frequency band opened up in TV white space to solve this Wi-Fi frequency depletion problem is under consideration (see FIG. 19 and Non-Patent Document 1 cited below). However, this band is 6-8 MHz, which is narrower than the bandwidths (22 MHz, 20/40 MHz) for conventional Wi-Fi use, and the scheme is that several to tens of users share radio waves. Therefore, if the number of users or the amount of information transmitted per unit user is large, the available band will be restricted.
Thus, an attempt to secure a wide band in such a scheme that multiple bandwidths in the same frequency band are aggregated or aggregated with a heterogeneous radio band (heterogeneous multi-radio network) has been made to transmit and receive large volumes of data smoothly like in video transmission using a Wi-Fi network where the available band is restricted. As schemes for transmitting packets in this heterogeneous multi-radio network, various schemes have been considered, such as to distribute the packets into two radios based on the throughput or the amount of delay measured on the receiver side, or to separately use a lower radio depending on the characteristics of an application.